The use of swing flaps fitted to doors to allow the independent exit and entry of pets without having to continually open and close the door, also to prevent any damage to the door as a result of scratching and knocks made by the animals, is a known fact.
An opening is generally made in the door, close to the ground, bordered by a support frame equipped at the top with pins designed to act as hinges for the flap to swing open as a result of the pressure exercised by the animal and close by means of gravity.
It is currently possible to use flaps connected to servomechanisms, for example a linear actuator, which can be controlled by special electronic units that can receive a signal from a transmitter on the collar of the animal wishing to pass through the flap, thus preventing undesired entries and exits.
Current background art also includes solutions that foresee the use of electromagnetic devices consisting of a reed switch and a diode on a circuit, which is closed by the entry or exit of the pet wearing a collar fitted with a magnet. In this case too, closure of the circuit enables the movement of a linear actuator designed to open and close the flap.
There are also electronic type solutions using a transponder which dialogues with a special electronic unit which is designed to control the opening and closing of the flap by means of actuators of various types.
One disadvantage is represented by the fact that the presence of the pet inside the house is not indicated in any way, a difficult situation especially if the pet is small and thus sometimes difficult to find.
Another disadvantage is represented by the fact that flaps controlled by electronic or electromagnetic devices are relatively expensive and are also not very reliable. These devices may in fact not be enabled as a result of abrupt movements of the animal or other accidental reasons, not least the loss of a collar fitted with a transmitter or a magnet.